Removal of invasive tree improves health of American Samoa forests

Mar 26, 2012

Removal of the Tamaligi tree (Falcataria moluccana), an invasive and destructive non-native tree on Tutuila Island, American Samoa greatly improves the health of its diverse native forests, according to a recently published study appearing in the journal Biological Invasions.

A team of scientists from the USDA Service's Pacific Southwest Research Station–Hilo and the National Park of American Samoa (NPSA) investigated how Tamaligi affected the composition, biomass, and soil nitrogen in forests within or adjacent to the NPSA. The team sampled both forests with Tamaligi, and forests where Tamaligi had been present, but subsequently removed.

Native to the Moluccas, New Guinea, New Britain, and the Solomon Islands, Tamaligi was introduced to Tutuila Island in the early 1900s. Aided by its nitrogen-fixing capacity, Tamaligi—among the world's fastest growing trees—thrives on a variety of soil types, including degraded sites and acidic or nutrient-poor soils. By 2000, 35 percent of Tutuila Island was infested with the invasive tree, prompting NPSA to begin control of this species.

Since 2001, there has been an aggressive field campaign to eliminate the Tamaligi tree within the boundaries of the NPSA and surrounding areas. Invasive species control in general, and control of the Tamaligi tree in particular, is considered a high priority as Samoa's forests are important constituents of the Pacific Ocean's Polynesia/Micronesia biodiversity hotspot. These islands support some of the most intact native ecosystems of any Pacific Island group, including shoreline, or littoral, communities, wetlands, and lowland, montane and cloud rainforests.

Findings from the current study demonstrated the strong influence of Tamaligi on the structure, composition, and functioning of American Samoa native forests. That Tamaligi-invaded forests exhibited equivalent levels of total biomass, but significantly lower biomass of native tree species, suggests that this invasion replaces, rather than augments, the biomass of native trees in these forests. But once Tamaligi trees are controlled, the native trees quickly recover and shade out any future Tamaligi regeneration.

"The effort to eliminate Tamaligi populations from the NPSA is a great and inspiring example of successful control of an invasive species," says Dr. R. Flint Hughes, a PSW research ecologist who led the study. "Funding effectively supported the control efforts. Widespread public support was garnered through outreach with local village leadership, employment of villagers, and use of the media. And even though Tamaligi is a daunting invasive, it can be controlled, and when it is, many of the native Samoan tree species recover and persist."

Explore further: Nestling birds struggle in noisy environments

More information: To read the full article, go to: treesearch.fs.fed.us/pubs/40018

add to favorites email to friend print save as pdf

Related Stories

Faster koa tree growth without adverse ecosystem effects

Mar 27, 2008

U.S. Forest Service scientists with the Institute of Pacific Islands Forestry have completed a study on ways to make high-value koa trees grow faster, while increasing biodiversity, carbon sequestration, scenic ...

Stranglers of the tropics -- and beyond

Mar 25, 2011

Kudzu, the plant scourge of the U.S. Southeast. The long tendrils of this woody vine, or liana, are on the move north with a warming climate.

Recommended for you

Nestling birds struggle in noisy environments

22 hours ago

Unable to fly, nestling birds depend on their parents for both food and protection: vocal communication between parents and offspring helps young birds to determine when they should beg for food and when they should crouch ...

The secret life of the sea trout

Oct 29, 2014

Jan G. Davidsen and his graduate students are spies. They use listening stations and special tags they attach to their subjects to track their movements. They follow their subjects winter and summer, day ...

Giant tortoises gain a foothold on a Galapagos Island

Oct 28, 2014

A population of endangered giant tortoises, which once dwindled to just over a dozen, has recovered on the Galapagos island of EspaƱola, a finding described as "a true story of success and hope in conservation" ...

Fish "personality" linked to vulnerability to angling

Oct 28, 2014

Individual differences in moving activity in a novel environment are linked to individual differences in vulnerability to angling, according to an experimental study completed at the University of Eastern Finland and the ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.